Breastfeeding and supplementing with formula at night

This guide was originally published on May 5, 2019 in NYT Parenting.

When I was a new mother, I heard so much about the advantages of breastfeeding over formula feeding that it felt like my only options were either breast milk or formula. So much so that it seemed like a revelation when I finally realized I could do both at the same time.

I was not alone in this realization, of course. Many women successfully combination feed — a practice that involves giving babies formula in addition to breast milk. According to the Centers for Disease Control and Prevention, one out of three breastfeeding mothers in the United States supplements her breast milk with formula by the time her baby reaches 6 months of age.

Many women find that their babies switch between breast and bottle and between breast milk and formula with ease. For others, there are hiccups along the way.

To help you get started combination feeding and manage any potential problems, I reviewed the published data and spoke with several experts, including Dr. Marianne Neifert, M.D., a pediatrician practicing in Denver; Freda Rosenfeld, a board-certified lactation consultant based in Brooklyn, N.Y.; and Dr. Michael Kramer, M.D., a professor of pediatrics at McGill University in Montreal.

[Read our guide on breastfeeding during the first two weeks of life]

What to do:

• Introduce a bottle early, but not too early.
• Start slowly, use the right nipple, relax and enlist help.
• Do not force your baby to bottle feed.
• When dealing with bottle refusal, be patient.
• Prevent uncomfortable engorgement, leaking and clogged ducts.
• Maintain your milk supply while giving formula.
• Choose an iron-fortified formula.

Introduce a bottle early, but not too early.

The sweet spot for introducing bottles for full term babies is usually “between 2 and 6 weeks of age,” said Rosenfeld. If you do it before you and your baby are “in a groove with breastfeeding,” she warned, your baby may learn to prefer the faster, easier flow from the bottle and lose interest in the breast.

But even more important than age, according to Dr. Neifert, is whether “your baby is latching well, getting full feeds at the breast and gaining well.” Some babies get the hang of nursing sooner than others.

Once your baby is nursing effectively and gaining weight, however, don’t wait too much longer before introducing the bottle because the baby might reject it. Babies’ sucking reflexes typically start fading at around 6 to 8 weeks, so it’s best to introduce a bottle before this reflex has faded so your baby reflexively sucks on the bottle nipple.

Start slowly, use the right nipple, relax and enlist help.

Start by offering bottles filled with just a half ounce or so (of breastmilk or formula).

If your baby has been exclusively breastfed, Rosenfeld recommended starting with a wide, slow flow nipple that mimics the shape and flow of your own nipples, decreasing the chance that your baby will find it easier to get milk from a bottle than the breast.

A baby older than 3 months, however, may become frustrated with a slow flow bottle, especially if mom’s breasts have a fast flow, Rosenfeld warned. In that case, she recommended trying a faster flow nipple.

To ensure that baby is happy, relaxed and not too hungry, offer a bottle one to two hours after your baby’s last feeding. Crying is a late sign of hunger, and a hungry baby is easily frustrated.

If you are the first to offer the bottle, your baby may refuse and insist on nursing. (She knows who has the good stuff, after all.) Instead, ask your partner or another familiar caregiver to offer the first few bottles, if you can. This will not only help your baby get used to bottle feeding, but will help establish a feeding relationship with your partner (if you have one), too.

Whomever is giving the bottle should try to relax and follow your baby’s cues. Babies sense stress and may reject a bottle if the person offering it seems anxious.

Do not force your baby to bottle feed.

If your baby refuses the bottle at first, do not force him to drink. Wait and try again later, an hour or two after their next feeding.Some studies have linked early overfeeding with an increased risk of later obesity.

“For most healthy, full-term infants, parents can look to their baby rather than the clock for hunger cues,” according to a webpage from the American Academy of Pediatrics. “This is called feeding on demand, or responsive feeding.”

When bottle feeding, watch for signs your baby has had enough: turning away, pushing away the bottle, spitting out milk, chewing on the nipple, gagging or falling asleep. (This video from the A.A.P. describes these signs in detail.)

Unlike breast milk, leftover formula in a bottle your baby has drunk from cannot be saved. Check out this A.A.P. guide to safely preparing formula.

When dealing with bottle refusal, be patient.

Rarely, a breastfed baby will prove shockingly tenacious in refusing to take milk from a bottle. If after trying all of the above techniques your baby is still rejecting the bottle, or if your baby begins refusing the bottle after taking it previously, you can also try:

Distracting the baby. Try giving the bottle when your baby is calm and a little distracted, for example, by offering a bottle while taking a walk outside.

Heating things up. Try warming the milk and the bottle nipple, to make the experience more similar to feeding at your breast.

Offering a taste. Using a syringe, try dribbling a little milk into your baby’s mouth and then giving her the bottle. This helps trigger her drive to suck on the bottle.

Using music as a feeding cue. Rosenfeld recommended playing the same music while nursing and bottle feeding. This cues your baby that it’s time to eat.

Bypassing the bottle. If your baby is 6 months or older, try circumventing the bottle and weaning directly onto a cup.

Prevent uncomfortable engorgement, leaking and clogged ducts.

When you start introducing formula, your breast milk production will take a few days to adjust to the reduced demand. In the interim, your breasts may become uncomfortably engorged, which can lead to embarrassing leakage, clogged ducts or even mastitis — a painful infection of the breast tissue.

Thus experts generally advise introducing formula slowly, gradually replacing breastfeeding sessions with formula feeding.

One method is to replace one nursing session per week with a formula feeding session. Start by giving your baby one bottle of formula at around the same time each day. This will train your body to stop producing milk at that time.

Another way to start introducing formula, according to the National Childbirth Trust, a nonprofit based in Britain, is the “top it off” method, which involves giving a small amount of formula (half an ounce to an ounce) after a nursing session. The extra nourishment will make your baby feel more full, extending the time until your next nursing session and gradually reducing the amount of milk you produce at that time.

If your breasts still become engorged, “you can relieve some of the pressure by pumping or hand expressing a little milk, but only until you feel relief,” said Dr. Neifert. She warned against “draining your breasts completely, as that signals to your breasts to continue to produce milk.”

[How to keep pumping when you return to work]

Maintain your milk supply while giving formula.

If you wish to maintain your milk supply while giving formula, you may need to breastfeed or pump frequently, up to 8 to 12 times per day. The exact number of times will depend on your breasts’ storage capacity and the age of your baby.

According to the N.C.T., if your baby is older — around 8 or 9 months — you can usually maintain your breastmilk supply alongside formula feeding, as long as you breastfeed every day.

The Department of Agriculture has tips for maintaining your milk supply while introducing formula.

Choose an iron-fortified formula.

For healthy, full term babies who are partially breastfed, the A.A.P. recommends a cow’s milk-based formula that is iron-fortified. (Low-iron formulas raise your baby’s risk of anemia.)

Infants younger than 1 year should never receive regular cow’s milk or any other milk in place of formula or breast milk. Cow’s milk does not contain the proper balance of nutrients your growing baby needs.

A few babies, such as those with lactose intolerance, severe reflux or milk allergies may need a special formula. Talk with your baby’s pediatrician if you think your baby needs one.

If you need more help choosing a formula, consult The Wirecutter’s Guide to the Best Baby Formula. (The Wirecutter is a New York Times company that does rigorous product reviews.)

Understand that bottle feeding and breastfeeding place different demands on your baby.

To breastfeed effectively, babies must open their mouth wide, latch on to the breast and then coordinate a suck, swallow and breath sequence. Bottle feeding, by contrast, provides a continuous flow of milk; instead of working to extract the milk, babies only need to pause the flow of milk in order to breathe.

Because of these differences, some babies will develop a strong preference for the bottle or, less often, for the breast.

Nipple confusion. Women sometimes receive dire warnings that artificial nipples, including pacifiers, can lead to nipple confusion — or an inability to latch on to the breast and effectively extract milk.

“ … these concerns [over nipple confusion] can cause significant stress for new mothers who are struggling with breastfeeding,” Dr. Chad Hayes, M.D., a pediatrician practicing in Charleston, S.C., wrote on his blog.

For example, La Leche League, a nonprofit focused on breastfeeding advocacy, warns that many mothers have “noticed a change in her baby’s sucking patterns after introducing a bottle or a dummy [pacifier]. Her baby may struggle and cry, find it difficult to latch on, or simply nurse ineffectively at the breast.”

Fortunately, according to Dr. Hayes, these fears are overblown. A recent meta-analysis of randomized controlled trials, for instance, found that among full-term babies, bottle feeding and pacifier use had no apparent impact on the duration of breastfeeding. After reviewing the research, Hayes concluded that “nipple confusion doesn’t seem to play a huge role in infant feeding.”

(Among preterm babies who, for health reasons, often need to start on bottles before breastfeeding is established, bottle feeding has been linked with a slightly shorter duration of exclusive breastfeeding.)

Flow preference. While true nipple confusion is rare, a more common cause of a baby fussing at the breast or refusing to latch is flow preference.

Flow preference occurs when your baby can still breastfeed effectively but prefers the fast, easy flow of milk from a bottle. Babies who prefer bottles may fuss, cry or push you away when you try to nurse. Some babies may temporarily refuse to nurse at all, going on a nursing strike.

If this happens, La Leche League recommended hand expressing a bit before trying to latch your baby onto your breast. This helps to reduce engorgement and to get the milk flowing, so that your baby is rewarded with milk immediately after latching. The Australian Breastfeeding Association also offers several tips for handling breast refusal.

If your baby is still resisting breastfeeding, Rosenfeld recommended taking a bottle holiday for at least a week. When you reintroduce the bottle, you can try paced bottle feeding, a method of giving bottles designed to emulate breastfeeding. It involves sitting your baby upright or only slightly reclined, holding the bottle horizontally so your baby has to suck to extract milk from the bottle, and allowing for frequent pauses between gulps of milk.

If you are having persistent problems getting your baby to latch or to breastfeed effectively, seek outside help. The United States Lactation Consultant Association website can help you find a board-certified lactation consultant near you.

Feel good about your choice.

The A.A.P. recommends that women breastfeed exclusively for about the first six months of life, and then continue breastfeeding while giving solid foods for at least a year.

Exclusive breastfeeding for six months — without additional solids or formula — provides the strongest protection against gastrointestinal and respiratory infections during infancy. But partial breastfeeding does still provide some protections against diarrhea, ear infections, Sudden Infant Death Syndrome and respiratory infections like pneumonia.

Note though, that “this protection against infection lasts only as long as you are breastfeeding,” said Dr. Kramer.

Some studies also suggest that breastfeeding can confer additional lifelong protection against obesity, eczema, asthma and allergies, as well as a slight boost in I.Q., though many of the studies showing these long-term benefits “have major methodological issues,” according to the A.A.P.

Women sometimes hear that just one drop of formula will change a baby’s microbiome — the mélange of bacteria, fungi, and other microscopic bugs that line the skin and gastrointestinal system. Such changes, they are warned, may have lifelong consequences for their babies’ immune and metabolic health.

While formula-fed babies do have a different balance of bacteria in their gut microbiome, said Dr. Kramer, “we still do not know how this relates to later health.” And, Dr. Kramer added, many things, such as antibiotics, how they were born and the types of foods they eat, can also alter the microbiome.

Some popular breastfeeding websites also warn that using formula can “shorten the breastfeeding relationship.”

But this depends on your situation. I and many of my mom friends found that giving some formula helped us sustain breastfeeding by lessening its logistical, physical and emotional demands.

When to Worry

Cutting down on breastfeeding may cause your breasts to become engorged with milk, which can lead to clogged milk ducts. You may notice a hard, red and tender lump on your breast that feels warm to the touch. A clogged duct will often occur only in one breast.

To help clear the duct, nurse and pump frequently to keep your breast from becoming full of milk. Massaging your breast and applying warm compresses while nursing or pumping may also help the duct clear and ease discomfort.

If you also develop shivers, chills or other flu-like symptoms, you may have mastitis, a serious infection of the breast tissue. Mastitis can come on suddenly and cause you to feel weak and achy. If you think you may have mastitis, contact your doctor right away; you may need antibiotics.

Amy Kiefer, Ph.D., is a freelance science writer and mother of three who blogs on pregnancy and breastfeeding for Expecting Science.